An Indian police constable who was seriously injured during a massive demonstration against a brutal gang rape has died in a New Delhi hospital.

Authorities say the policeman died Tuesday, two days after he was attacked by a mob that clashed with police.

Sunday's unrest took place as police struggled to control protesters who have expressed increased outrage over the rape and beating of a 23-year-old medical student earlier this month.

The student was attacked after she and a male friend were given a ride on a chartered bus in New Delhi on December 16. Officials say a group of men raped and beat her with an iron rod, then threw the woman off the bus.

The woman remains hospitalized in critical condition on respiratory support.

Officials have barricaded roads and closed some metro stations in the capital in a bid to end the demonstrations.

On Monday, Indian Prime Minister Manmohan Singh called for calm. In a televised address, Mr. Singh also vowed to examine issues affecting the safety of women and children.

Many protesters have demanded the death penalty for the suspects now in detention.

More than 600 cases of rape have been reported in New Delhi so far this year, one of the highest rates in the country.